The primary objective of this study is to investigate the function of the metal ion complex in metalloproteases. The study will focus on the construction of the best possible model for the active site metal ion complex in carboxypeptidase A. The design of these models will take into consideration a) the influence of the metal ion, b) the influence of the geometry about the metal ion, c) the effect of incorporating into the model additional functional groups postulated to be involved in catalysis by the enzyme, and d) the influence of substrate sterochemistry. Crystallographic and spectroscopic studies in our laboratories suggest that certain zinc (II) and cobalt (II) amino acid chelates which we have designed more closely resemble the "entatic" environment proposed for the zinc metalloproteases than any simple complexes known. These complexes will serve as the framework upon which the models will be designed. Certain cobalt (III) chelates have been found to exhibit esterase and peptidase activity. Due to the relatively inert nature of these complexes it has been possible to investigate in detail the stereocehmistry involved in the hydrolyses. The information gained from these studies will be important in the construction of the enzyme models, and it is therefore proposed to continue these investigations. In the case of the simple peptides it has been shown that cobalt(III) hydrolysis is N-terminal and stoichiometric. Continuation of our investigation of the hydrolysis of the more complex peptides by these chelates, then, may lead to a new and perhaps advantageous approach to the sequencing of polypeptides.